Disallow dlarray in prototype

Using `dlarray` in a prototype results in `dlarray` in the output, but without the dimension labels. Reason: `cast(X,'like',Y)` behaves that way for `dlarray` `Y`.

Given that we do not return higher-dimensional data anyway, it is questionable whether there is any reason one would want to allow `dlarray` in prototypes. Not handling them properly means we are better off disabling them altogether.

Without a dependency on Deep Learning Toolbox, we cannot have an automated test point for this change, unfortunately.

+llms/+internal/jsonSchemaFromPrototype.m

@@ -27,7 +27,7 @@
         schema = struct("type","string");
     elseif isinteger(prototype)
         schema = struct("type","integer");
-    elseif isnumeric(prototype)
+    elseif isnumeric(prototype) && ~isa(prototype,'dlarray')
         schema = struct("type","number");
     elseif islogical(prototype)
         schema = struct("type","boolean");